Abstract: An oscillator circuit is a closed loop including an amplifying circuit and a feedback circuit. The amplifying circuit includes a pair of amplifiers, which also function as impedance buffers, and a first phase-shift circuit. The feedback circuit includes a second phase-shift circuit and a piezoelectric vibrator. The second phase-shift circuit is capable of adjusting the phase and gain of the feedback circuit. The first phase-shift circuit of the amplifying circuit is arranged between the pair of amplifiers and is separated, in terms of impedance, from the second phase-shift circuit. The first phase-shift circuit is capable of adjusting the phase of the entire closed loop.